Method of Measuring Body Temperature Hits the Mark Under Alice Analysis

In Exergen Corp. v. Kaz USA, the Federal Circuit held that patents directed to a “body temperature detector” and related methods were eligible under § 101. The patents at issue disclose a body temperature detector that calculates a person’s core temperature by detecting the temperature of the forehead directly above the superficial temporal artery, and applying a constant coefficient to the skin and ambient temperature readings. After the jury found the claims infringed and not invalid, the district court denied judgment as a matter of law that the claims were directed to ineligible subject matter. The Federal Circuit affirmed the § 101 holding.

Under the Alice test, the court first determines whether the claims are directed to a patent-ineligible abstract idea. If so, the court then examines the elements of the claims to determine whether the combination contains an inventive concept sufficient to transform the claimed abstract idea into a patent-eligible application. Unsurprisingly, the Federal Circuit found the claims abstract at step one. The parties, however, disputed whether the additional claimed steps “beyond calculating the temperature” added an inventive concept sufficient to confer patent eligibility.

As an initial matter, the Federal Circuit gave “clear error deference” to the district court’s conclusions that the claimed elements were not well-understood, routine, or conventional. Something is not well-understood, routine, and convention merely because it is disclosed in a prior art reference. Even if the concept of measuring core body temperature is directed to a natural phenomenon and is abstract at step one, the measurement method was sufficiently inventive. “Following years and millions of dollars of testing and development, the inventor determined for the first time the coefficient representing the relationship between temporal-arterial temperature and core body temperature and incorporated that discovery into an unconventional method of temperature measurement.” Citing evidence presented at trial and from the patent specifications, the district court held the patents eligible at Alice step two. This was not clear error.

The Federal Circuit did not decide whether the Seventh Amendment guarantees a jury trial on factual underpinnings of the § 101 analysis, finding that Kaz waived its right to a jury trial for the § 101 factual issues. Judge Hughes dissented, arguing that the novel heat-balance coefficient was not sufficient to confer eligibility on the combination of well-understood, routine, and conventional elements.

Although designated nonprecedential, the opinion offers guidance for prosecuting and litigating against a § 101 challenge involving diagnosis claims, and sets the scene for a future case on whether there is a right to a jury trial on the factual underpinnings of a § 101 determination.

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